In accordance with the Electricity Business Act, a power producer and supplier (PPS) is requested to match a used power amount and a supplied power amount (simultaneous commensuration) on a 30-minute basis. Nevertheless, even for the 30-minute basis, it is difficult for a power producer and supplier to completely achieve the simultaneous commensuration, and some excess or shortage possibly arises. When such an excess or shortage arises, the local electric power company supplements the shortage or absorbs the excess. When having supplemented the shortage, the electric power company asks the power producer and supplier for an “imbalance rate”. Therefore, in order to adjust the supply amount, the power producer and supplier has a power storage system so as to achieve the simultaneous commensuration.
When using the power storage system, it is important to predict a chargeable or dischargeable electricity amount (amount of a charge) or power amount of a storage battery in the power storage system at any time point. Incorrect prediction results in a difficulty in fluctuation suppression and peak shift to be achieved, which can cause the imbalance rate. Therefore, a charge/discharge amount prediction system is used. The charge/discharge amount prediction system is used, other than for the power storage system, also for power generation using natural energy such as solar power generation and wind power generation, and power generation using an electric vehicle, a hybrid electric vehicle and the like.
The chargeable/dischargeable electricity amount of a secondary battery largely changes due to environmental temperature, deterioration over time and the like. Therefore, in general, a state of charge (SOC) of the secondary battery, a temperature of the secondary battery, and the like are set as parameters, a standard chargeable/dischargeable maximum power value under the parameters is experimentally obtained, and it is beforehand listed in a table as a characteristic value table. A charge/discharge power value with arbitrary parameters has been predicted on the basis of this characteristic value table.
However, since prediction of the charge/discharge power value as above is based on a standard across-the-board characteristic value table, characteristic variation among individual secondary batteries and characteristic deterioration advancing over time cannot be dynamically handled, which causes a large error in charge/discharge power prediction value. Therefore, the prediction value is to be estimated to be small in order to secure an operational margin, which results in a charge/discharge amount prediction system practically low in performance.
Meanwhile, there is a method by which characteristic variation and deterioration progress can be handled by performing test charge/discharge for every fixed period, updating characteristic value data, and based on the result, predicting chargeable/dischargeable power. Nevertheless, such test charge/discharge takes time, and accuracy in instantaneous input/output control is low. Moreover, during the test charge/discharge, there arises a difficulty in achievement of simultaneous commensuration, and handling of fluctuation suppression, peak shift and the like, which can cause the imbalance rate, also being practically low in performance.